The post-tensioned anchorage zones of several thin-webbed box girders, which were designed in accordance with AASHTO and ACI requirements, have cracked along the tendon path during stressing. This cracking presents paths for potential corrosion and frost damage. In addition, such cracking negates a major benefit of prestressed concrete, namely, the minimization of service load cracking. This report summarizes the major design-related observations and conclusions from an extensive analytical and experimental study of the behavior of post-tensioned anchorage zones with single large tendons. The experimental program considered variables such as tendon inclination and eccentricity, anchor width and geometry, and the effect of supplementary anchorage zone reinforcement. Three- dimensional computer analyses were used to generalize these results. A failure theory developed to explain tendon path crack initiation agreed well with the experimental data. A general equation for cracking load in specimens without supplemental anchorage zone reinforcement is presented along with provisions for designing supplementary reinforcement and calculating the effect it will have on cracking and ultimate load. Suggested code and commentary changes, based on the results of the above mentioned data, are presented. Examples showing practical applications of the tentative recommendations are included.
